A dishwasher is a device that removes filth, such as food waste, from dishes or cooking tools (hereinafter, referred to as ‘objects to be washed’) using detergent and wash water.
A dishwasher generally includes a washing tub having therein a washing space, a rack provided in the washing tub for receiving objects to be washed, a spray arm for spraying wash water to the rack, a sump for storing wash water, and a supply channel for supplying the wash water stored in the sump to the spray arm.
In general, the dishwasher uniformly sprays wash water to objects to be washed, such as dishes, while rotating the spray arm for spraying the wash water to wash the objects. In recent years, there has been developed a dishwasher further including an auxiliary arm configured to roll along an arc track of a spray arm in order to spray wash water, in addition to the spray arm, which is configured to spray wash water during the rotation of the spray arm using rotational force generated when the spray arm is rotated.
Such a dishwasher is disclosed in Korean Patent Application Publication No. 10-2012-0126598, in which the dishwasher has a structure in which wash water is sprayed upward through a nozzle of a spray arm disposed in a washing tub.
In some implementations, when wash water is sprayed to objects to be washed, such as dishes, it is necessary to uniformly spray wash water to the surfaces of the dishes. Consequently, it is necessary to spray wash water at various angles. In a conventional dishwasher, a spray arm is rotated to rotate a spray nozzle. In order to achieve more efficient washing, however, it is necessary to vary the spray angle.